Characterization of Alkanolamine Blends for Carbon Dioxide Absorption. Corrosion and Regeneration Studies

There are a lot of research programs focusing on the development of new solvents for carbon dioxide capture. The most important priority should be reducing the energy consumption needed at the regeneration step, but minimizing solvent degradation and its corrosivity is also considered as a priority. In this research, the aqueous blends of 2-amino-2-methyl-1-propanol (AMP: 1 kmol·m−3) and 1-amino-2-propanol (MIPA: 0.1–0.5 kmol·m−3) are characterized in terms of density, viscosity, and surface tension. The carbon dioxide absorption rate and capacity, the regeneration capacity, and the corrosivity of these solvents are also evaluatedFinancial support for this research was obtained under the Project UJA 2016/08/07: “Development of more efficient solvents for carbon dioxide capture-2” (I+D+i Support Plan of the University of Jaen), for which we are gratefulS

Influencia del grado de deformación en frío en el tamaño de grano y en la resistencia a la corrosión del acero F-1110

En este trabajo se ha estudiado la evolución que sufre el tamaño de grano del acero al carbono F-1110 para distintos grados de deformación en frío, a partir de su estado de recocido, libre de tensiones y de cualquier acritud. La deformación en frío se ha conseguido utilizando una máquina universal de ensayos y los distintos grados de deformación se han ajustado al intervalo comprendido entre la estricción y la rotura. La posterior observación al microscopio óptico de las zonas deformadas, previa preparación metalográfica, nos ha permitido medir la variación en el tamaño de grano. Finalmente, se ha evaluado la influencia del grado de deformación en la resistencia a la corrosión del acero

Magnetic hardening of Fe30Co70nanowires

3d transition metal-based magnetic nanowires (NWs) are currently considered as potential candidates for alternative rare-earth-free alloys as novel permanent magnets. Here, we report on the magnetic hardening of FeConanowires in anodic aluminium oxide templates with diameters of 20 nm and 40 nm (length 6 μm and 7.5 μm, respectively) by means of magnetic pinning at the tips of the NWs. We observe that a 3-4 nm naturally formed ferrimagnetic FeCo oxide layer covering the tip of the FeCo NW increases the coercive field by 20%, indicating that domain wall nucleation starts at the tip of the magnetic NW. Ferromagnetic resonance (FMR) measurements were used to quantify the magnetic uniaxial anisotropy energy of the samples. Micromagnetic simulations support our experimental findings, showing that the increase of the coercive field can be achieved by controlling domain wall nucleation using magnetic materials with antiferromagnetic exchange coupling, i.e. antiferromagnets or ferrimagnets, as a capping layer at the nanowire tips.We acknowledge funding from the European Community's Seventh Framework Programme (FP7-NMP) under grant agreement no. 280670 (REFREEPERMAG)

An extraordinary chiral exchange-bias phenomenon: Engineering the sign of the bias field in orthogonal bilayers by a magnetically switchable response mechanism

[EN] Isothermal tuning of both the magnitude and the sign of the bias field has been achieved by exploiting a new phenomenon in a system consisting of two orthogonally coupled films: SmCo (out-of-plane anisotropy)-CoFeB (in-plane anisotropy). This has been achieved by using the large dipolar magnetic field of the SmCo layer resulting in the pinning of one of the branches of the hysteresis loop (either the ascending or the descending branch) at a fixed field value while the second one is modulated along the field axis by varying the orientation of an externally applied magnetic field. This means the possibility of controlling the sign of the bias field in a manner not reported to date. Moreover, modulation of the bias field strength is possible by varying the thickness of a spacer between the SmCo and CoFeB layers. This study shows that the observed phenomena find their origin in the competition between the artificially induced anisotropies in both layers, resulting in a reversible chiral bias effect that allows the selection of the initial sign of the bias field by switching (upwards/downwards) the magnetization in the SmCo film.This research was supported by the Joint German-Spanish Actions Programme (DAAD and Fundación Universidad.es via Ref. 57050243), the Spanish Ministerio de Economía y Competitividad (MINECO) through “SIESPER” (MAT2011-25598) Project, and the Regional Government of Madrid through NANOMAGCOST (P2018/NMT-4321) project. D. S. acknowledges financial support from Xunta de Galicia under the postdoctoral program I2C Plan (Modalidade B) and the Strategic Grouping in Materials (AeMAT; grant No.ED431E2018/08). IMDEA Nanoscience is supported by the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D, MINECO [grant number SEV-2016-0686]Electronic supplementary information (ESI) available. See DOI: 10.1039/c9nr08852

Stochastic vs. deterministic magnetic coding in designed cylindrical nanowires for 3D magnetic networks

[EN] Advances in cylindrical nanowires for 3D information technologies profit from intrinsic curvature that introduces significant differences with regards to planar systems. A model is proposed to control the stochastic and deterministic coding of remanent 3D complex vortex configurations in designed multilayered (magnetic/non-magnetic) cylindrical nanowires. This concept, introduced by micromagnetic simulations, is experimentally confirmed by magnetic imaging in FeCo/Cu multilayered nanowires. The control over the random/deterministic vortex states configurations is achieved by a suitable geometrical interface tilting of almost non-interacting FeCo segments with respect to the nanowire axis, together with the relative orientation of the perpendicular magnetic field. The proper design of the segments' geometry (e.g. tilting) in cylindrical nanowires opens multiple opportunities for advanced nanotechnologies in 3D magnetic networks.Spanish Ministry of Science and Innovation under Projects MAT2016-76824-C3-1-R, PID2019-108075RB-C31/ AEI / 10.13039/501100011033 and PGC2018-097789-B-I00 and the Regional Government of Madrid under Project S2018/NMT-4321 NANOMAGCOST-CM. LA and MF acknowledge project RTI2018-095303-B-C53.Peer reviewe

Magnetic properties of spinel-type oxides NiMn2-xMexO4

New materials, based on the well-known spinel compound NiMn2O4, have been synthesized and characterized from the magnetic point of view. The manganese cation was partially substituted in the general formula NiMn2-xMexO4 , by nonmagnetic and magnetic elements, such as Me = Ga, Zn, Ni and Cr (0 x 1). Prior to the determination of their magnetic properties, the non-substituted spinel NiMn2O4 was carefully characterized and studied as a function of the oxygen stoichiometry, based on the influence of the annealing atmosphere and quenching rate. The ferrimagnetic character was observed in all samples, with a paramagnetic-to-ferromagnetic transition temperature Tc stabilized at 110 K, and well defined long-range antiferromagnetic interactions at lower temperatures, which depend on the applied field and the substitute concentrationAuthors from Chile and O.P. thank projects Fondecyt-Chile 1020066, 7020066 and 1050178. Authors from France and Brazil thank project CAPES/COFECUB 416/03. Authors from France thank Région Bretagne for financial supportPeer reviewe

Electrochemical nucleation and growth of Fe, Pt and Fe–Pt on n-type Si (001)

Electrodeposition of Fe, Pt and Fe–Pt on n-type Si (001) wafer was studied. The electrochemical nucleation and growth mechanism was investigated using conventional electrochemical techniques and morphological examinations. The current transients recorded during potentiostatic deposition were compared with the non-dimensional plots predicted by the Scharifker-Hills theory indicating that there exists a progressive nucleation mechanism for the electrodeposition of iron and platinum on the silicon substrate. Using different methods it was shown that the diffusion coefficient of iron ions is about three times larger than that of platinum ions. All single and multi-component system studied reveal 3D multiple nucleation with diffusion controlled growth

CoFeCu electroplated nanowire arrays: Role of composition and annealing on structure and magnetic properties

CoxFe100-x and CoxFe95-xCu 5, with 30 < x < 90, arrays of nanowire, around 20 nm in diameter and about 5 μm long, have been prepared by electrodeposition filling the self-assembled nanopores of anodic alumina templates. These samples were later thermally annealed for 2 h in the range of temperatures up to 600 °C. Crystalline anisotropy was confirmed to exhibit bcc cubic structure with [110] texture in as-prepared state. First structural changes are observed after annealing at 450 °C when a refinement of such cubic phase is observed. Annealing at higher temperatures promotes the appearance of Co and Fe oxides. Small addition of Cu to CoFe alloys induces only limited variations in the magnetic properties for as-prepared samples. Nevertheless, the presence of small Cu content promotes a significant magnetic hardening in comparison with the effect observed in CoFe nanowires. From the temperature dependence of magnetic properties in as-prepared and annealed samples we conclude a complex contribution of various anisotropy energy terms coming from the annealing and from the presence of Cu. The presence of Cu in small amount induces significant changes in the magnetic properties of annealed CoFeCu nanowires. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.This study has been supported by the Spanish Ministerio de Economia y Competitividad under Project MAT2010-0278-C05-01, and the European Community’s 7th Framework Program, under Project REFREEPERMAG, Grant Agreement No. 280670.Peer Reviewe

Vortex domain wall propagation in periodically modulated diameter FeCoCu nanowire as determined by the magneto-optical Kerr effect

Control over the magnetization reversal process of nanowires is essential to current advances in modern spintronic media and magnetic data storage. Much effort has been devoted to permalloy nanostrips with rectangular cross section and vanishing crystalline anisotropy. Our aim was to unveil and control the reversal process in FeCoCu nanowires with significant anisotropy and circular cross section with tailored periodical modulations in diameter. Magneto-optical Kerr effect measurements and their angular dependence performed on individual nanowires together with their analysis allow us to conclude that the demagnetization process takes place due to the propagation of a single vortex domain wall which is eventually pinned at given modulations with slightly higher energy barrier. In addition these results create new expectations for further controlling of the propagation of single and multiple domain walls.The authors acknowledge support from the Spanish National Research Council under project 201460E014, from the Spanish Ministerio de Economia y Competitividad under project no. MAT2013-48054-C2-1-R, and from the European Community's 7th Framework Program under project no. REFREEPERMAG, grant agreement no. 280670. info:eu-repo/grantAgreement/EC/FP7/28067

Angular dependence of coercivity with temperature in Co-based nanowires

The magnetic behavior of arrays of Co and CoFe nanowire arrays has been measured in the temperature range between 100 and 300 K. We have paid particular attention to the angular dependence of magnetic properties on the applied magnetic field orientation. The experimental angular dependence of coercivity has been modeled according to micromagnetic analytical calculations, and we found that the propagation of a transversal domain wall mode gives the best fitting with experimental observations. That reversal mode holds in the whole measuring temperature range, for nanowires with different diameters and crystalline structure. Moreover, the quantitative strength of the magnetocrystalline anisotropy and its magnetization easy axis are determined to depend on the crystalline structure and nanowires diameter. The evolution of the magnetocrystalline anisotropy with temperature for nanowires with different composition gives rise to an opposite evolution of coercivity with increasing temperature: it decreases for CoFe while it increases for Co nanowire arrays.This work has been performed under the auspices of the EU Commission under REFREEPERMAG Project, Grant Agreement No. 280670 and of Regional Government of Madrid under Project Nanobiomagnet, S2009/MAT-1726. A.P. E. and J.E. acknowledge the support from Fondecyt 1150952 and Center for the Development of Nanoscience and Nanotechnology CEDENNA FB0807. Conicyt Ph.D. Fellowships Program is also acknowledged